Coal or rock drill.



G.- G. MAYER & R. ASHTON.

GOAL OR ROCK DRILL.

' APPLICATION FILED SEPT. 9,1908.

914,966, Patented Mar. 9, 1909.

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no. 914,9cs.

Specification of Letters Patent.

Patented March 9, 19 09.

Application filcdscptember 9, 1908. Serial No. 52,181. l T

To all whom it may concern:

Be it known that we, GEORGE G. Mnre' and Reese Asrrros, citizens of the United States, residing'at South Bethlehem, in the county of Northampton and State oi Pcnnsylvania, have invented new and useful lm-- provements in Coal or Book Drills, of which the following is a specification.

This invention relates to drills intended vision of a simple and convenient insane whereby the various tools can be clamped in position on the head of the drill and at the same time permits one or more of the drills to beretracted when not required. for use according to the nature of the substance drilled.

With these objects in view and others, as will-:tppear as the description proceeds, the invention comprises the various novel featurcs of construction and arrangement of arts which will be more fully described ereinaftcr and set forth with particularity in the claims appended hereto.

In the accompanying drawing which. illustratcs one of the embodiments of the invention, Figure 1 is a front view of the drill. Fig. 2 is a side view thereof. Fig. 3 is a transvcrse section on line 3-3, Fig. 1. Fig. 4 is a front view of the drill showing one of the tools retracted for converting the drill from four-to three cutters for the purpose of drilling relatively soft substances.

Similar reference characters are employed to designate corresponding parts throughout the several views.

Referring to the drawing, A designates the head of the tool which is of any suitable muterial and size and on the head is a shank 1 of suchshu-pe as to be applied to a drill chupk or extension therefor. The front and rear sides of the head are flat and taper downwardly as shown in Fig. 2 and in these fiat faces are shallow dove-tailed grooves 2, the

single bolt 6 passing "through an opening 7 located in the longitudinal center line of the head and provided with clam iug plates 8 that have their side edges bcve cd or under 7' cut at thirty degrees so that each plate will bear against the inneni'aces of each, respective pair of cutters. ,The clamping plates not cnlyhold the cutters against the fiat bot-- tom surfaces of the grooves 2 but by their wedging. action force the cutters outwardly or apart into firm engagement withthe undercut shoulders 5 of the dove-tailed grooves. By partially lcoscniru the bolt 7 the cutters can be independently adjusted longitudinally so as to thereb vary the diameter of the bore which the rill will make, and the cutters can be filed down from time to time as they become dull and then projected still] the substance is soft, like coal, four cutters will be found unnecessary and in thls case one of the outside cutters can be retracted as shown in Fig. 4, and clamped in position so that there will be only three eil'cctive cutters, and the fourth can be held in reserve to take the place of any other cutter that may become dull or broken. In hard substances, such as rock, the fourth cutter will be set to do its share of the Work with the others. It will be noted that one pair of cutters is disposed revcrsely to that of the other and are beveled in opposite directions, their cutting edges being set approximately to coincideon a line extending transversely of the axis of rotation. With a'lilrill of this character the user can readily sharpen tools or cutters when necessary so that the need of a skilled workman for sharpening the tool is unnecesssry as was formerly the case, and further more the drill can be adjusted for holes of various sizes.

From the foregoing description, taken in connection with the accompanying drawing, the advantages of the construction and of the method of operation will be readily apparent to those skilled in the art to which the invention appeitains, and while we have described the principle of operation of the in vention, together. with the apparatus which We now consider to be the best embodiment thereof, we desire to have it understood that the apparatus shown is merely illustrative, and that such changes may be made when desired as are within the scope of the claims ap ended hereto.

Taving thus described the invention, hat is claimed as new is zv 1. A drill comprising a head having tapering opposite faces having spaced undercut 5 wells, the walls on one side of the head being 1 inclined oppositely from those of the other side, a pair of cutters disposed at opposite sides of thehead and engaging under said eieece walls, and a cl amping plate disposed between each pair of cutter for holding the same in engagement with the head and serve to wedge the cutters apart to interlock under the said Walls. Y

2. A drill comprising a head having rela tively shallow dove-taiiedgrooves in its opposite faces and ificlined oppositely to each other, a pair of cutters disposed parallel to each other and movable longitudinally in each groove, a clamping plate disposed between each pair of cutters, anct forcing the sarneapart to engage the undercut wall'sof the grooves and clamping the cutters into contact with the bottoms of the grooves,

; plates to the cutters.

1 In testimony whereof we affix our signal tures in presence of two witnesses GEORGE G. IrlAYlrlli.

REESE ASHTON" I Witnesses:

I A. L. (lore,

1 WILLIAM Brr'rsnn.

and a common means for tightening the 

